In her tiny flat on the edge of Kursk, Irina Tsymbal shows me a piece of metal.

It is charred and covered in rust - the kind of scrap you normally would not think twice about discarding.

But for Irina this is worth more than gold: it is a piece of the Kursk submarine, and a reminder of her husband Ivan. He was a warrant officer on the sub which sank in the Barents Sea.

Five years on, Irina still remembers the lies that rained down from the Russian navy.

"The navy chiefs only told us something was wrong three days after the accident," Irina recalls. "They assured us the crew were alive, that they'd all be saved. I believed them. I'd always been told the Kursk was unsinkable."

It was not. On 12 August 2000, a torpedo exploded on board during a military exercise. One of the country's most modern subs was crippled on the seabed.

Ivan Tsymbal was one of 118 men who died in the icy waters of Barents Sea. Back then President Vladimir Putin was slammed for being slow to react and appearing reluctant to call in foreign assistance.

Ivan's remains were recovered when the Kursk was lifted a year later. He is now buried in a war cemetery in Kursk - the city which had supplied the sub with recruits, equipment and a name.

Fallen heroes

Irina shows me Ivan's grave - he is buried next to 11 of his comrades. As we walk around the simple memorial, Irina lays purple carnations on each of the graves.

The Kursk was once the pride of the Russian navy

"They're all heroes," she says. "Not because they died. But because they were submariners. Each time they went on an underwater mission they were heroes defending their motherland."

This is a country which has grown wearily accustomed to tragedy - the Kursk cemetery is a testament to that. Here are mass graves from World War II and the graves of Russian soldiers killed in action in Chechnya. And now submariners from the Kursk.

Russia knows how to honour its fallen heroes - but is it capable of learning from its mistakes?

"Five years after the Kursk, we still don't have an effective rescue service for our submarine fleet" military analyst Pavel Felgenhauer told me.

"These submariners go out to sea on suicide missions. Because if something goes wrong they know that no one will come to their aid, they're on their own. Only if the Russian navy decides to call in the Americans or Brits to save them."

Mini-sub drama

Last week another Russia sub got into trouble. Tangled up in nets and cables, it was trapped at the bottom of the Pacific Ocean. This time Moscow called for help much more quickly.

A Royal Navy underwater rescue robot was airlifted to Kamchatka. In just a few hours it had managed to cut the sub free and save the crew.

Irina Tsymbal wishes that prompt help had been requested for the Kursk.

"I'm sure that some of the crew at the back of the Kursk were still alive more than a day after the accident," Irina says. "If rescuers had got to them more quickly, I'm sure that they could have been saved."

Pavel Felgenhauer predicts more incidents at sea.

"We're prone to accidents in Russia," he says. "We've already had a few close shaves. In February 2004, in the presence of President Putin, two ballistic missiles got stuck in a submarine's silo during a firing exercise. That was a very dangerous situation."

Irina took me to the edge of Kursk to see a new monument to the stricken submarine. It is made out of part of the Kursk's hull and will act as a permanent reminder of the disaster. But in her family memories of Ivan are starting to fade.